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Just Let Them Eat the Marshmallow

Judging a kid's ability to delay gratification by whether they eat a marshmallow or not is a ridiculous way of predicting their future achievement, say Po Bronson and Ashley Merryman.

No behavioral game has gained more publicity in the last year than Dr. Walter Mischel’s “marshmallow test,” an assessment of children’s impulse control. Four-year-olds are put at a table in a blank room, with a marshmallow in front of them. They’re told that if they can wait until the experimenter comes back, they’ll get two marshmallows to eat. Writing about this in The New Yorker last spring, Jonah Lehrer reported that preschoolers who waited the full 15 minutes grew into teens with SAT scores that were, on average, 215 points higher than the tots who ate the marshmallow in the first 30 seconds.

David Shenk also writes about the marshmallow experiment in his forthcoming book,
The Genius in All of Us, and New York magazine's Jennifer Senior endorsed it as The Test to Beat. Senior declared: “[M]y money’s on the marshmallow test.... It seems as good a predictor of future success as any.” Readers have since eagerly echoed her recommendation.

View a video of the infamous marshmallow test.

Is Senior right? Is the Marshmallow Task as accurate (or better) than any other test, and thus the answer to early testing?

Sorry, but no.

First, it’s the easiest test in the world to fool. Parents can just promise their kid a pony if they don’t eat any marshmallows or cookies during the evaluation session.

Second, reportage of the marshmallow study has obfuscated just how few kids were included in Mischel’s analysis. While 550 kids participated in the experiment, Mischel only tracked down SAT scores for 94 kids. The vast majority of those kids did not participate in the original, classic marshmallow task. Instead, their marshmallow was covered from view, or they were given a pretend scenario to distract themselves with. In these other conditions, if a kid could hold out for 15 minutes, it meant their SAT scores were much lower, not higher. The correlation was
negative.

It was actually only 35 kids who did the classic test—17 boys and 18 girls. How long they waited was a lot worse predictor for the boys than the girls. And while about a third waited the full 15 minutes, it was only a handful of kids who ate the marshmallow in less than 30 seconds.

So all this hype about the Marshmallow Task’s incredible ability to determine SAT scores comes from a handful of tots who were hungry—way back in the late 1960s.

Only one attempt to replicate the long-term outcomes of Mischel’s study has ever been done. That was by the University of Connecticut’s Inge Marie-Eigsti a few years ago. Her team tracked down kids who’d done the Marshmallow Task (except with cookies) at the Barnard Child Toddler Center in the early 1990s. They tracked down 34 kids who’d done the classic task (only one less than Mischel’s team). Eigsti’s team didn’t even bother to ask for SAT data, because they didn’t expect much variation, but they did give the now-18-year-old teens a full IQ workup, and they also ran the teens through tests of “executive function,” which is the brain’s system that governs self-control.

Eigsti’s team found that how long they could avoid eating the cookie, when they were 4 year olds, had zero correlation to IQ or self-control at age 18. Zero.

Like Mischel, Eigsti had a handful of kids—five—who ate the cookie in under a minute. But these kids also were noted to demonstrate a lot of the symptomology of ADHD. Which could mean that the famous Marshmallow Task is just another way to identify kids with ADHD.

Eigsti does not feel her data disproves Mischel—he was actually a co-author on her paper, and she thinks her work is consistent. But she’s unequivocal about whether the marshmallow test should be used to determine entrance to private schools.

“Oh, good grief. Absolutely not,” she said. “There's not anyone on our team who would advocate for use of marshmallow tasks for school entrances or enriched programming. These measures don’t tell you about success rates. They should not be used that way.”

Po Bronson and Ashley Merryman's New York magazine articles on the science of children won the magazine journalism award from the American Association for the Advancement of Science, as well as the Clarion Award from the Association for Women in Communications. Their articles for Time magazine won the award for outstanding journalism from the Council on Contemporary Families. Bronson has authored five books, including the New York Times bestseller What Should I Do With My Life?